Insulating materials are solids used to isolate different electrical conductors. Generally, solid insulating mater...
Insulating materials are solids used to isolate different electrical conductors. Generally, solid insulating materials are also required to have a supporting role. Because of the higher density of solid insulating materials, the breakdown strength is much higher. The insulation resistance, dielectric constant and the range of changes of solid insulating materials are very wide.
Solid insulating materials can be divided into two categories: inorganic and organic.
Inorganic solid insulation materials: mainly powder mica and mica products, glass, glass fiber and their products, as well as electric porcelain, alumina film, etc. They are resistant to high temperatures, not easy to age, and have considerable mechanical strength. Some of these materials are low cost and occupy a certain position in applications.
The process of glass is simpler than ceramics and can be used for manufacturing. Glass fiber can be made into silk, cloth, and tape. It has much higher heat resistance than organic fiber and plays an important role in the development of insulation structure to high temperature.
Organic solid insulation materials: In the 19th century, they were mainly natural, such as paper, cotton cloth, silk, and curable vegetable oil. These materials are flexible, can meet the application process requirements, and are easy to obtain.
The silicone resin combined with the low-alkali glass cloth greatly improves the heat resistance level. Polyvinyl formal for enameled wire made of lacquer base has opened up the broad prospects of enameled wire, replacing silk covered wire and yarn covered wire. The thickness of the polyester film is only tens of microns. Using it to replace the original paper and cloth greatly improves the technical and economic indicators of motors and electrical appliances.
Aramid fiber paper, polyester film, and polyimide film are used together to make the heat resistance of the motor tank insulation grade F and H respectively. Elastomer materials also have similar developments, such as heat-resistant silicone rubber, oil-resistant nitrile rubber, and subsequently fluorine rubber and ethylene propylene rubber.